MDF window sills

[Lawrence Zarb]

What is the best most secure way to fix an mdf window sill to a breeze block wall?

[Andy Hall]

No More Nails or equivalent if you never want to remove it without damaging it.

Otherwise drill and counterbore, and make plugs from a piece of MDF. Screw the the cill to the wall and then fit plugs and sand over the top. These can be drilled out to gain access to the screws if you ever want to remove the cill.

[Mike Halmarack]

Cills usually go outside, window boards go inside.

[owdman]

In either case MDF is unsuitable as it is very prone to damp and will expand, bend etc

cheers

Jacob

[Mike Halmarack]

I hope you're wrong. I have great hopes of putting a newly painted corner unit made from MDF into my bathroom. I'm counting on several coats of paint to protect it from moisture.

[Cicero]

==================== I think you're safe with MDF. Wickes and other such places sell ready-made window boards - 1" with bull nose and ready primed. They must have faith in their product.

Cic.

[Sunshine Sid]

L shaped steel straps screwed to the underside of the board and then screwed to the wall work well. The straps are then hidden by the wall finish.

S

[meow2222]

MDF sills should be avoided. I know from experience that the surface degrades too quickly in real world use to be a product of any serious quality.

NT

[Andy Dingley]

It will last as long as the paint remains impermeable. Then it will turn into cheese. You can certainly do this, but I'd be wary of it.

A much better material is Valchromat - MDF with extra resin content, making it both water-resistant and also pre-coloured.

'd be amazed if an MDF outdoor sill lasted more than a winter or two.

[Weatherlawyer]

Why would he want to do that and if he ever needed too what would he need to spare it for?

Most people use matic fixers these days. You need a selection of packers as the blockwork is notoriously uneven. Also be prepared to chisel off some of the blockwork if it's too high.

You need to make sure it all fits first. The standard width that seems to be supplied these days doesn't cross the modern courses on some windows. You want it to come proud of any plasterboarding on the walls if thee is going to be some at a later date.

[Lawrence Zarb]

Just for everybodies reference

The "sill" or window boards will be on the inside not outside..

[sm_jamieson]

If you get a new build, the skirting, architraves and window boards will all be MDF. I suspect they are durable enough if painted properly. Simon.

[Roger]

The message from Mike Halmarack contains these words:

Not to most people, nor my dictionary for that matter.

[Collins]

Cill - variant spelling used in the building industry for sill (senses 1 - 4)

Sill - 1. a shelf at the bottom of a window inside a room

No entry for window board

[The Natural Philosopher]

It bends a lot less than softwood or hardwood.

[The Natural Philosopher]

MDF is totally fine until it gets sopping wet.

Then it turns into soggy cardboard. However it is impregnated with resin, especially at the surface. Watch out for end grain though..that CAN soak stuff up. Several coats of paint are advisable.

[.]

Just for everybodies (sic) reference, it's cill. LOL

[John Cartmell]

Sill comes from Old English syll, which in turn derives from the proto-Germanic/Indo-European words suljo/swel meaning beam. You find it as sulle, sille, svill, &c in various early Germanic languages. Never as cill - except that the OED allows cill as an occasionally used variant of sill. Occasionally by people who spell it wrong? ;-)

For everybody's reference. It's sill (or cill - but preferably sill). And it doesn't mean inside or outside - but either.

[meow2222]

Yeah, cost cotting all over

well, mine wasnt. Maybe others will be luckier. I guess I just dont see much sense in installing something that will be a mess in 5 years when you can have real wood that will look good next century.

Enjoy your mdf!

NT

[Chris Cowley]

Exterior-grade MDF has been available for a quite a while - at least fifteen years. I remember when it was first introduced, my Dad (who works in the timber industry) had an un-painted/un-varnished piece which he left out in the back garden for a couple of years by way of a test and it suffered no ill effects, other than attracting a bit of surface moss/mould.

I don't know what it's bonded with to make it weatherproof - probably some variety of nasty chemical or other!

[Mike Halmarack]

So, of all the developments and variations in meaning and spelling throughout the ages, those used currently in the building industry are the ones disqualified from use by you? Sounds very John Cartmell to me. :-)